Wet chemical analyses often include a series of operations that ultimately produce a desired measurement or characterization. One step often involves the delivery of predetermined volumes of one or more fluid chemicals into a mixing chamber. In some cases known ratios of chemicals are mixed and the resulting mixture is then analyzed to determine one or more properties of the mixture and/or its constituents. Some analyses may also characterize the mixture and/or its constituent parts based on one or more reactions occurring in the mixture.
When performed by hand, chemical analyses can produce varied results due to a number of factors such as, for example, the usage of an improper or inaccurate volume of a fluid chemical. Moreover, manual analytical chemistry procedures can be tedious and time consuming. Current attempts at automating steps in a chemical analysis provide some benefits over manual procedures, but drawbacks persist. For example, circumstances may require an increased sampling frequency that current manual and automated analysis methods and systems cannot accommodate with required accuracy and precision. Often large volumes of chemicals and/or fluid samples are also needed for analysis with current systems and methods, leading to expensive and wasteful operation.
One application of analytical chemistry is to determine the concentration of one or more analytes within a composition. For example, analytical chemical procedures can be useful in the analysis and monitoring of antimicrobial compositions. Antimicrobial compositions are used in a variety of automated processing and cleaning applications to reduce microbial or viral populations on hard or soft surfaces or in a body or stream of water. For example, antimicrobial compositions are used in various applications including kitchens, bathrooms, factories, hospitals and dental offices. Antimicrobial compositions are also useful in the cleaning or sanitizing of containers, processing facilities or equipment in the food service or food processing industries, such as cold or hot aseptic packaging. Antimicrobial compositions are also used in many other applications including but not limited to clean-in-place systems (CIP), clean-out-of-place systems (COP), washer-decontaminators, sterilizers, textile laundry machines, filtration systems, etc.
Whatever the application, an antimicrobial or “use” composition is a composition containing a defined minimum concentration of one or more active components which exhibit desired antimicrobial properties. One such category of active antimicrobial components include peracids, such as peroxycarboxylic acid (peracid), peroxyacid, peroxyacetic acid, peracetic acid, peroctanoic acid, peroxyoctanoic acid and others.
The concentration of active components in the use composition is chosen to achieve the requisite level of antimicrobial activity. In use compositions in which one or more peracids are the active component, and in the instance of a recirculating process, the concentration of hydrogen peroxide tends to increase over time while the concentration of peracid decreases. However, in order to maintain the requisite level of antimicrobial activity, the amount of peracid in the use composition must be maintained at a defined minimum concentration. In addition, as the amount of hydrogen peroxide in the use composition increases, the use composition may exceed a defined maximum concentration of hydrogen peroxide in the solution. In some applications, for example bottling line cleansing, the allowable amount of residual hydrogen peroxide is subject to government regulations. Once the hydrogen peroxide concentration exceeds the maximum concentration, the spent use composition is discarded and a new use composition generated.
To ensure that the amount of peracid is maintained at or above some minimum concentration and to determine when the amount of hydrogen peroxide reaches or exceeds a maximum concentration, it is necessary to determine the concentration of peracid(s) and hydrogen peroxide in the use composition. In the past, to determine properties such as the peracid concentration and the hydrogen peroxide concentration in a use composition has required multiple time consuming manual titrations, several different reagents and relatively large volumes of use composition. Also, past automated systems designed to address one or more of these undesirable traits have also exhibited less than desired sampling frequency and difficulties with online deployment in the field.